1. Field of the Invention
This invention relates to material(s) handling and is particularly, but not exclusively, concerned with the unitary or `one-shot` handling of relatively large, bulky, cumbersome or multi-component loads as a single entity.
2. Description of the Prior Art
Unitary handling is an advantage when loading and unloading turn-around times are critical.
The term `load` embraces any kind or form of material, whether single or multiple items, packaged or loose--without particular restriction upon overall volume, configuration or weight.
Similarly, the term `handling` embraces any action or treatment which it is desired to apply to a load, or constituent parts of the load--and indeed the very initial load formation and subsequent load dissolution or dismantling.
In most instances such handling will imply some mobilization, i.e. enabling movement, and including subsequent (typically linear translational) movement itself.
Either to facilitate handling, or as part of load positioning, some, albeit marginal, elevation of the load is also commonplace--e.g. simply to raise the load clear of a (ground) support surface.
Loads may be prepared ready for handling by virtue of their `packaging profile`, including a pre-assembled stack of individual component subsidiary loads, but the stack, whilst representing in its entirety the overall load to be treated or handled as a whole, may not itself have the inherent robust nature or integrity to facilitate such handling as a single entity.
For example, the load may be loose stacked cartons.
The invention is concerned in some (but not necessarily all) of its aspects with the handling of a load in its entirety, including the transfer of a previously assembled (multi-component) load into a pre-defined load space, such as a (vehicle) container, which is either unmodified or has minimal modifications or adaptations to receive the load.
Such transfer in a single continuous operation is also embraced.
An example would be the loading or unloading of an entire (e.g. containerised) vehicle load in a single operation.
A remote (i.e. not an integral part of the vehicle) loading or unloading facility for such `single-phase` operation is desirable, for use with different vehicles.
Essentially, load handling is a `temporary` special case of materials handling, i.e. a `given` or prescribed amount of material to be handled at a given time, on a given occasion, or over a given time span; and generally a case where external restrictions or limitations in mechanical practicalities associated with the nature of the load itself, are placed upon the volume, configuration or weight of the material to be handled at any such one time.
In that regard, material may be produced in a form which suits, or is a compromise between the requirements of the producer, along with any interim stockists and ultimate consumer, for the intended market, but may not be particularly suited to the available external carriage or transport facilities, which are generally outside the control of the producer.
Thus the consumer may require only a single goods unit at one time, whereas manufacturing economies of scale and storage dictate a minimum multiple unit number, and on occasion an intermediate breakdown therebetween being the responsibility of a wholesaler and possibly retailer chain.
However the external transport industry may pay no direct attention to any of these considerations.
Whilst the transport industry has sought to standardize loads for efficient handling through different transport media, i.e. road, rail, sea and air--in particular by adopting standard available load capacity through containerization, some load characteristics do not lend themselves readily to containerisation or in particular the loading into containers. Thus the potential economies of scale of bulk load transport are difficult to realise.
A `container` has prescribed shape and volume upon a given base floor area, along with a maximum loaded weight, and may be physically enclosed with side and end walls and a roof, or some of these may be omitted, with a limiting case of a simple load platform with some tie down and stacking points.
Enclosed containers pose particular loading constraints, since loading from above is precluded by the container roof and apart from curtain-sided variants loading is generally restricted to one narrow end.
For example, at one end of the scale, bulk individual loads such as steel girders have hitherto not readily been containerised, not least because of the impracticality hitherto of loading the attendant distributed weight from one end--i.e. the load centre of gravity is difficult to approach with conventional loaders.
At another extremity, small unit loads, such as cans of foodstuffs or drink may have to undergo several successive packaging steps, e.g. cartons or crates, stacked upon pallets and shrink wrapped for stability, to fill a container--i.e. they cannot economically be loaded individually, and even when grossed into larger multiple units, these are still much less than an individual container capacity.
In this latter case, no practical means has hitherto been identified for loading a container, in a `single-shot` operation, with a full complement of multiple cans--i.e. several hundred or even several thousand, cans at one time.
Both these load examples are characteristically static, or with no inherent mobility, whether in the packaging or otherwise.
Introducing such mobility through the medium of the load handler has an associated penalty in `handling space`.
A container has predetermined associated handling costs, regardless of its actual contents, i.e.(subject to special commercial tariff arrangements) an empty container costs as much to handle and transport as a full container.
Thus a container generally represents a bulk load capacity to be filled as completely as possible, by a typically multi-component or fragmented load, minimizing wasted voids and within the prescribed weight limitations--and also without undue packaging, which represents a load `denial` (or wasted additional load opportunity) and an unproductive associated expense overhead.
This represents so-called `volumetric efficiency`.
Without being unduly theoretical, the load handling problem may thus be analysed in relation to three main components, namely:
I. the (physical) space (i.e. floor area and overall volume) occupied load itself (to be handled); PA1 II. the (theoretically ultimate) available load space or capacity; and PA1 III. the (physical and notional supplementary maneuvering, load mounting and dismounting) handling space required by the load handling facility. PA1 A. Trucks or trolleys; and PA1 B. Conveyors PA1 accumulating multiple individual subsidiary loads into an assembly corresponding cumulatively to a grosser load capacity; PA1 capturing the loads as a unitary grosser load; PA1 elevating the unitary load; PA1 transporting the unitary load to another spaced location; PA1 lowering and depositing the unitary load at that other location; disengaging and withdrawing the transporter from the load.
For efficient load handling, (i.e. maximizing the use of the available load capacity) the difference between available load space or capacity II and the load I must be minimized; i.e. minimal unused or wasted load space--whether, say, (in the case of containerized handling) by virtue of peripheral/ancillary load packaging or `awkwardness`, or incompatibility of the load shape in relation to a container interior.
However, the handling space III must also be compatible with the available load capacity II--i.e. the handling facility must be able to fit physically, at least in part into that capacity, in order to introduce and withdraw the load in relation thereto.
In addition, the load handling space must align closely with the minimized difference between I and II--i.e. with minimal wasted load capacity, the load handling must still be able to operate, from start to end of the loading sequence.
It will be appreciated that, as the available load space starts to fill, there is progressively less intrusion of the load handling which can be accommodated, although in principle there may be an attendant reduction in the need for such intrusion, as the load is introduced along one loading direction or axis.
In a practical sense, for container loading, the handling device may have to fit within the container. Not least because of the inherent fragmented nature of many, if not most, container loads--i.e. the container load capacity is many times an individual load component--it is commonplace to introduce the load components individually, as what will hereinafter be referred to for convenience as multiple `subsidiary` loads.
For fragmented or multi-component loads, two known broad categories of load handling device are:
Trucks or trolleys are typified by independently-mobile fork-lift trucks and pallet trolleys--usually restricted to a single, or a relatively few component (e.g. palletized) loads, at least in relation to an overall container capacity.
Moreover, these are essentially, `discrete` or one-off/one-at-a-time loaders.
European Patent Application No. 0 133 042 teaches an elevatable track-running, load handling trolley variant.
Conveyors, whether roller beds or continuous belts are, in contrast, `continuous` loaders, but generally restricted to one location, or, if mobile, are inherently unwieldy, by virtue of their long and narrow configuration.
European Patent Application No. 0 000 321 teaches an elevatable mobile roller conveyor variant.
Both of these handling device categories have been adapted for containerized loads, with a uniform overall load profile, which facilitates subsequent storage and handling--i.e. a larger stack of containers can be formed and vehicles and load handling equipment, such as cranes and side-loader lifts, may have standardized fittings to receive such containers.
Such uniformity may be extended within the container, by adopting subsidiary component loads themselves also of a (lesser) uniform profile, by palletization or even `miniature` containers.
Palletized loads are generally stackable, so that any irregularity of the individual load items does not undermine the regularity of the overall load profile--although there may necessarily be voids within the container.
Indeed, any vehicle with a predefined load space and load volume imposes corresponding constraints upon the nature of its load capacity--i.e. in short, the load must be tailored to fit the vehicle/container.
If the load can be broken down into relatively small and regularly shaped components. then--given enough time, skill and patience, and some discretion in load component selection--virtually the entire load space can be filled, at least manually.
In that regard, it is also known to automate the formation of an individual (palletized) load stack, e.g. from a collection of cartons of individually known configuration, fed to by a conveyor, from a continuous production source or an intermediate stockpile, to a palletized load formation station, where they are deposited in succession upon a palletized floor until a stack of desired proportions and weight has been formed.
These cartons may be coded, e.g. by bar coding, to reveal their identity to a selection and loading mechanism.
Thereafter the thus palletized load may be `integrated` or formed into a unitary collection, e.g. by shrink wrapping, to give the palletized load stability in subsequent handling.
Thus, for example, in the canned soft drinks field, it is known both to shrink wrap a tray of cans and a stack of palletized wrapped cans, to enable secure handling by a fork lift truck.
However, such palletized load automation has hitherto generally been restricted to a relatively small individual pallet and not the formation of an entire vehicle container load from a succession of pallets.
Palletized loads lend themselves to handling by conventional relatively small-scale, general purpose un/loading vehicles, such as fork lift trucks, which can readily be used to fill long vehicle open-sided containers or decks from the exposed accessible vehicle (longitudinal) sides, side cover sheets, doors or shutters then being closed to conceal and protect the load or the load covered overall by a tarpaulin and roped or strapped in position.
For containers accessible only at one end, fork lift trucks may be used only to introduce the load at that end, with subsequent movement being effected manually, albeit with the assistance of bearing surfaces on the vehicle floor or individual pallet trucks.
However, this may not be practicable for the generality of loads which might have to be carried and thus wasted voids arise in the load capacity.
In the materials handling industry it is common-place to employ pallets as an intermediary between the load and a load support.
The term pallet is used herein generally to embrace any form of platform or other ancillary load support, including load suspensions or side braces, upon which a load may be rested or otherwise mounted for subsequent storage and transit.
Conventional pallets, as an underside or platform floor, are typically of a spaced timber planking lattice construction, in order to support a load for storage and transit.
The pallet provides a ready means of grasping the load and bearing its weight, for example by using the support arms/tines/prongs of a fork lift truck to locate through the pallet depth.
To facilitate this the pallet has either a twin opposed reversible slatted deck surface with spaced intervening bearers, or a single deck with support ribs.
However, there has hitherto been a practical limit to the size, and in particular surface area, of pallet employed as such an ancillary support, because of the inherent strength and bulk requirements of the pallet, which add to the overall bulk of the storage mass and otherwise intrude into the available load storage space/volume.
As such, a conventional pallet construction large enough to cover the entire available load area of a vehicle, whether containerized, box body or open flat deck has not been feasible. In particular, the bending loads on the pallet would be excessive.
Even if such a pallet could be constructed, there is presently no facility for lifting and moving it as a whole, let alone inserting it into a vehicle body and withdrawing the load mechanism.
Again the bending moments for a load of such overall length and weight, necessarily supported only from a remote end, would be burdensome and difficult to engineer.
Thus, it is common practice to form a composite bulk load larger than an individual pallet capacity from an assembly of several (say, longitudinally) aligned individually palletized subsidiary loads.
Handling pallets one-at-a-time, is laborious and time consuming--but handling several pallets securely at one time is problematical.
One approach that has been adopted to facilitate the formation of bulk loads from fragmented components is a combined conveyor and load support platform.
For example, a vehicle container load deck may have integral bearing surface incorporating rollers spaced over the load deck for moving parts of the load around the deck, with means to lock or withdraw those rollers into an inoperative (non-load contacting) condition.
UK Patent No. 2,126,189 teaches one such a `bespoke` roller deck, for integration with a vehicle or container floor.
A similar roller load deck may be used at the un/loading station for the assembled load ready for un/loading.
The individual load components can then be rolled, either singly or as a group, from the assembled stack on to the (vehicle) container.
As the initial load reaches the end of the container, it is brought to a halt, with a slipping drive contact thereafter as successive loads accumulate progressively.
More elaborate such roller decks also incorporate a drive mechanism, such as a friction-grip slipping chain or belt, so that the deck combines the functions of a conveyor.
Thus continuous runs of power driven decks may be used to transport loads, typically palletized so that a pallet may engage the drive mechanism, over long runs.
However, such a specialized load deck represents an elaborate and expensive solution, which is only economically justifiable when the loading and unloading cycle time is significant in relation to the vehicle average journey time--i.e. relatively short delivery runs, of, say, 10 miles or less.
It would thus be advantageous to be able to form the entire vehicle load, even for say a full sized container to international standards (for the UK generally up to 40 ton weight in a 12 m.times.2.5 m.times.2.5 m volume), and transport it directly in a single loading operation into the container, without requiring a specialized container load deck.
The length of this load deck, typically of the order of some 40 feet, is a critical factor in loading from one of the narrow ends.
That is to reach inside the 40 feet carrying a load on a mechanism which does not unduly infringe upon the load volume capacity and to deposit that load and retract is a major engineering feat with conventional approaches--the functional equivalent being the deployment of say a fork lift truck with a 40 foot arm reach.
In some applications such a full load could advantageously be made up of standard pallets, typically 1000 mm.times.1200 mm in surface area, but handling a fully palletized load at one time (rather than in successive `bites` or steps) has not hitherto proved feasible.
Although the foregoing discussion has centered upon container loading, and in particular palletized component subsidiary loads, the principles apply to any materials handling situation in which a load must be formed at a remote point from the source of load materials.
Thus warehousing situations are embraced where there is a requirement for lone-term load storage, and internal load re-location, e.g. before transfer to a loading station, ready for a vehicle container.